Hoechst in German Offenlegungsschrift No. 2,714,880 disclose antibacterially active cephalosporins including those of the formula ##STR6## wherein R.sub.3 is hydrogen; R.sub.4 is hydrogen or alkoxy; A is various 3-position substituents; and R.sub.2 is defined as alkyl of 1 to 4 carbons, for example methyl, having one or more substituents.
Hoechst in German Offenlegungsschrift No. 2,716,677 disclose antibacterially active cephalosporins including those of the formula ##STR7## wherein X is an .alpha.- or .beta.- --SO, or an SO.sub.2 group; R.sub.4 is hydrogen or alkoxy; A is various 3-position substituents; and R.sub.2 is defined as an alkyl of 1 to 4 carbons, for example methyl, having one or more substituents.
Takaya et al. U.S. Pat. No. 4,166,115 disclose 3,7-disubstituted-3-cephem-4-carboxylic acid compounds of the general formula: ##STR8## in which R.sub.1 may be a group of the formula: ##STR9## wherein R.sup.7 is amino or protected amino; R.sub.2 is an aliphatic hydrocarbon group which may have suitable substituents such as various heterocyclic groups, R.sub.3 is carboxy or protected carboxy, and R.sub.4 is methyl, acyloxymethyl, hydroxymethyl, formyl or a substituted heterocyclicthiomethyl group.
Heynes et al. in U.S. Pat. No. 4,152,432 discloses compounds of the formula: ##STR10## wherein R.sup.1 is selected from the group consisting of hydrogen, alkyl of 1 to 4 carbon atoms, alkenyl and alkynyl of 2 to 4 carbon atoms and groups easily removable by acid hydrolysis or hydrogenolysis.
Ochiai et al. in U.S. Pat. No. 4,098,888 discloses compounds of the formula: ##STR11## wherein R.sub.2 represents amino or hydroxyl group or a group convertible into these groups.